Summary by Sourcery

Prepare Flet 1.0 Beta Flutter package for pub.dev release and align code with latest Flutter APIs and color model changes.

New Features:

• Add Flet 1.0 Beta release entry to the package changelog.

Bug Fixes:

• Correct color handling utilities and Cupertino app bar opacity checks to work with the updated Color API and avoid precision issues.
• Fix semantics announcements by using the current implicit view and the updated SemanticsService API.
• Clean up unused state and properties in several controls to prevent unnecessary rebuilds and deprecations.

Enhancements:

• Update color-to-hex and darkening logic to operate correctly on double-based color components and clamp values safely.
• Modernize mock backend channel scenario methods with clearer naming and async signatures.
• Mark legacy slider and progress controls options with ignores for deprecated use while keeping behavior intact.

Build:

• Bump the flet package version to 0.80.0 and relax several dependency constraints to caret ranges.

CI:

• Adjust CI workflow to only publish on version tags, configure OIDC permissions for pub.dev trusted publishing, patch pubspec version on tagged builds, and simplify pub.dev publishing steps.